As hearing aids for persons hard of hearing, so-called bone-anchored hearing aids, including transducers, which are implanted in the temporal bones of such persons with hearing difficulty, namely, patients, have been proposed and put to practical use. The bone-anchored hearing aids are effective, particularly, for hearing-impaired patients due to a disorder of the external ear and/or the middle ear, hearing-impaired patients congenitally without formation of the external ear and/or the middle ear, and hearing-impaired patients with a relatively slight disorder of the internal ear. For utilization of such a bone-anchored hearing aid, it is necessary to form a required recess, usually a main recess for accommodation of a transducer and at least two auxiliary recesses (may be referred to hereinafter as sub-recesses) to which fastening screws for fixation of the transducer are to be screwed, in a required site of the surface of the patient's temporal bone, and then to accommodate the transducer in the required site and fix it there. The transducer is an element for vibrating a required weight at a high speed for bone conduction, and needs to have a required mass and a required volume. Thus, the recess for implantation of the transducer needs to be relatively large. The transducer is usually implanted between the temporal lobe of the brain and the sigmoid sinus, a large vein. A relatively large temporal bone exists at such a site and, in the case of a normal temporal bone without congenital malformation and without a past surgical history, surgery for forming the above recess is not necessarily a difficult operation for a skilled doctor. It is often the case, however, that the above-mentioned hearing-impaired patient has congenital temporal bone malformation, congenital middle ear malformation, active middle otitis, or a history of temporal bone surgery. In such a hearing-impaired patient, the accurate and precise formation of the required recess at the required site of the temporal bone is a very difficult operation even for a skilled doctor. To be appropriately aware of which site of the exposed temporal bone the recess should be formed at, and of whether the recess formed is of a required shape is extremely difficult, although not, impossible.
Medical navigation systems displaying the positional relationship between the target site for surgery in a patient during surgery and surgical instruments, such as a surgical knife, a surgical drill, and a robot hand, have been developed as this is well known. Patent Documents 1 and 2 to be cited below each disclose, in connection with such a medical navigation system, a registration template for use in the accurate recognition of the shape of the required site in the patient, for example, the shape of the bone surface; and a method for producing the registration template. No proposals have been made, however, for a surgical jig which is directly used in surgery to make it possible to accurately recognize a position where a recess is to be formed in the surface of a surgical target bone of a patient; and a verification jig for appropriately verifying whether or not the formed recess is of a required shape.